This relates generally to testing wireless electronic devices, and more particularly, to testing wireless electronic devices in over-the-air (OTA) radio-frequency test systems.
Wireless electronic devices typically include transceiver circuitry, antenna circuitry, and other radio-frequency circuitry that provides wireless communications capabilities. During testing, wireless electronic devices under test (DUTs) can exhibit different performance levels. For example, each wireless DUT in a group of DUTs can exhibit its own output power level, gain, frequency response, efficiency, linearity, dynamic range, etc.
The performance of a wireless DUT can be measured using an OTA test station. An OTA test station includes a test chamber with a test chamber antenna, a test unit, and a test host. The test chamber antenna is connected to the test unit and is used in sending and receiving radio-frequency (RF) signals to and from the test unit. The test host is connected to the test unit and directs the test unit to perform desired operations during testing.
During test operations, a wireless DUT is placed into the test chamber and communicates wirelessly with the test chamber antenna in the test chamber. Wireless transmissions of this type experience OTA path loss between the DUT antenna and the test chamber antenna.
An OTA test system typically includes multiple OTA test stations that are used to test multiple wireless DUTs in parallel. Each OTA test station typically includes its own test chamber, test unit, and test host. A production (factory) DUT is placed into the test chamber of each test station during product testing. Typical product testing involves measuring the wireless performance of each DUT and applying pass/fail criteria.
The radio-frequency path loss of each test station has its own unique OTA path loss characteristic. In an effort to provide accurate test measurement results across different test stations, conventional test methods involve calibrating the different test stations with golden DUTs (i.e., DUTs that exhibit known performance) to characterize the OTA path loss of each test station. OTA path loss may vary depending on the output power level of the wireless DUTs, operating frequency, test chamber configuration, test chamber antenna location, etc. As a result, OTA path loss characterization using golden DUTs to provide accurate measurements across different test conditions is an arduous and time-intensive calibration process.
It would therefore be desirable to be able to provide improved ways of testing wireless DUTs in a wireless test system.